What bhp from a road/race S2 engine?

[FritzPasadena]

Hi Guys,

What kind of horsepower can you realistically expect to get from a 'streetable' race engine in an S2 Elan? I want something that is reliable, potent enough for competition use but also practical for picking up a take away or school run. I'm thinking of having the original engine built for purpose but would it be more sensible to have a fresh motor made?

Thought I'd get some unbiased opinion from the forum - any and all ideas gratefully received.

Thanks.

[CBUEB1771]

You will have to make a few decisions before any answers from the forum make sense. You mention competition use. Do you mean club track days where rules are largely limited to safety equipment? Or are you thinking of more formal, sanctioned racing where you may find many limitations on what you can do to the engine? There will be many opinions on what is "streetable" as well. At least an S2 is light and pretty quick to start with. I would hesitate to look for more than 140 to 150 hp in a dual-use Twincam. This can be acccomplished by going to the longer stroke 1600 Kent crankshaft and increasing torque by a useful amount at the same. Formal race sanctioning bodies probably won't allow this modification however. Think about the basic rule of engine modification, the desired end points are high power, high reliability and low cost. Pick the two that you want in the same engine.

[FritzPasadena]

Thanks CBUEB1771,

The competition use would be Goodwood Revival / HSCC so it has to be pretty much 'period' in terms of mods. I'd rather not have the engine bored/stroked. 130-135bhp would seem about right from what your saying. Is this possible whilst retaining the original displacement?

Best,

[Dag-Henning]

Well, to run at Goodwood, you need to stick to the rules, being FIA App.K....They seem to be very strickt these days. A racing friend of mine from Norway ran his Lotus Cortina last time, - together with rally legend John Haugland -, and App. K was stricktly followed.......That means 4-bolt crank with small caps , small valves etc. I really do not think the cars that run at Goodwood Revival are suited for the road, the way that competion has turned.......However, if you insist to combine race and road, a 130-140 bhp sounds reasonable...... I would have 2nd thoughts though......

Dag

[rgh0]

Running road compression ratio of around 10.5:1 and 1558 to 1600cc displacement you can get around 150hp to perhaps 160 hp max at 1600 cc and 7500 rpm peak power using a 83.5 mm bore. This requires a top quality engine build but it is drivable on the street comfortably. If go to 12.5:1 comp ratio and run on racing fuel then up to 170hp possible in an Elan. In a Seven or Europa where you can fit a better exhaust up to 180hp possible. Not all mods permissible in various European historic racing as I understand so need to check details for eligibility if you want to race.

key mods

Steel crank, new flywheel, top quality rods, forged pistons, steel caps in bottom end to give 8000 rpm capability.
Short duration high lift cams and valve train to work with it to give both power and road usable torque curve
Big valves and top quality porting.
Top quality big bore exhaust header system
34 or 36 mm chokes and suitable jetting in carbs to work ok at part throttle on road as well as flat out at max power. A change to 45DCOE or flowing of 40 DCOE
Distributor and ignition system that works to 8000 plus rpm
Radiator cooling system that handles the extra heat rejection from a 160 hp engine.
Sump mods to ensure oil feed in RH corners, oil cooling also advisable for racing

The above is not cheap - around A$12,000 for parts and specialist machining if starting with a standard twink for a rebuild and doing all the dismantle / assembly work yourself. With the hp you get, you will also need to rebuild most of the rest of drive train to the wheels which costs more

cheers
Rohan

[rgh0]

I dont have to live with FIA app K valve size restrictions in Australia so if you impose those you may need to knock around 5 to 10 hp off my numbers

cheers
Rohan

[Greg Foster]

Rohan,
I was talking to a supplier in california regarding rebuilding of my tc. I will be installing a crank from a 1600 Pinto engine with the longer throw and rods He would supply the forged pistons to fit the application. I am looking for about 150 to 160 hp with a 10.3:1 c.r.. As we were talking he mentioned using higher lift cams with a longer duration saying the short duration cams were old information and that higher compression on the t.c. liked the longer duration cam. Any thoughts? Could you debate the points for and against? Other opinions would greatly be appreciated.
Greg

[garyeanderson]

Talk to some other engine builders in the U.S.

John McCoy at Omnitech
http://www.omnitech-engineering.com/aut ... bum1Pg.asp

or any of the other west coast builders. Rohan can also offer an opinion with a lot of experiance behind it.

Gary

p.s. - whos this engine guy?

[rgh0]

Greg

Building a long stroke, high capacity, high horse power road engine appears to be your aim.I assume you are building one with around 1700 cc and tuned for maxium power with a usable road torque curve.

10.3 is good comp ratio to aim for in road use. This is not a high compression engine in my terms but a normal European spec road compression.

You can get around 150 hp at 7000 rpm with a non steel bottom based on a std ford cast iron crank to this spec. You have to run it to 7000 rpm to get the 150 hp and the crank and 125E rods are getting marginal at these revs so you need to ensure you have a good rev limiter and do a number of other mods for reliability

You need a cam with around .44 lift and 280 to 290 duration. This is high lift and short duration in anybodys terms. A longer duration will be a waste of time as you will get even less hp below 7000rpm from a .44 lift 310 or 320 degree duration racing cam plus a torque curve with a big hole in it around 3000 to 4000 rpm which makes driving on the road a real pain in the ass.

You also need very good porting and carbs and exhaust to reach 150 hp.

To get above 150 hp you need to get revs above 7000 rpm which means a lot more money fro a stell bottom end.

Incidently it is the long duration cams which are the old racing technology of 20 years ago. The best racing cams these days for twinks are in the 280 to 300 degree region as they are quicker even if they produce a little less ultimate power at 8500 rpm due to better torque curves. Talk to Dave Bean or QED or John McCoy about the cams they supply and why

cheers
Rohan

[Greg Foster]

Thanks for everyones information. I am not going to name names and will educate myself further for a better grasp of what you have told me. I certainly don't want to rev my engine to 7grand just to obtain 150 hp but I do want a very streetable car with the most umph available in the 3000-6500 rpm range. More so torque is important. I am, at this time just spitting back info which may or may not be viable since I have no firsthand experience......I will search out info from the COMP CAM website and any others I can find. Beyond the durability of the bottom end, it seems the head is where the H.P. is. Right now the block, rods, crank and flywheel are at the machine shop being analised for the build. Head is there also. I am going on the faith of someone elses guidance.
Greg